The Brain

• • Localisation of brain function is where certain functions (memory, speech, language) have specific locations in the brain 
• The brain is split into two hemispheres, this is the right and left hemisphere
• The two hemispheres are connected by the corpus callosum, which acts as a bridge between the two hemispheres and allows them to send messages and work together
• Each hemisphere has 4 brain lobes
• Frontal Lobe:

  Motor control (premotor cortex)

  Problem solving (prefrontal area)

  Speech production (Broca's area)
• Temporal Lobe:

  Auditory processing

  Language comprehension (Wernicke's area)

  Memory/information retrieval
• Parietal Lobe:

  Touch perception (somatosensory cortex)

  Body orientation

  Sensory input
• Occipital Lobe:

  Sight (visual cortex)

  Visual reception and interpretation
• There is also the cerebellum that controls balance and coordination and the brain stem, which controls involuntary responses
• Phineas Gage was a railroad worker in the USA
• One day Phineas' tamping iron went through his head when an explosion went wrong
• The rod went through Phineas' chin and out through the top of his head
• Phineas did not lose consciousness and he could speak throughout the incident and recovery
• He recovered well eventually after suffering from a bad infection
• Apart from losing his sight in his left eye and some scarring, Phineas recovered physically well from the injury
• Phineas was changed psychologically after the accident
• Before the accident, Phineas was described as a calm and well-mannered individual
• After the accident, Phineas showed unreliable, rude and hostile behaviour
• Localisation


  The idea that specific areas of the brain are responsible for specific functions
• The personality change can be explained by the damage to a specific area of the brain


  This supports the idea of Localisation
• Hemispheric Lateralisation

  The brain is split into two equal symmetrical parts, the right and left hemispheres

  The brain is contralateral

  The left side of the body is controlled by the right side of the brain and vice versa

  If someone has a stroke in the left part of the brain, it will be physically evident on the right side of the body, such as that side of the mouth will drop or weakness in the limbs on the right side of the body

  Hemispheric lateralisation is the division of functions between the two hemispheres
• Left Hemisphere

  The left hemisphere for most people is where they process language

  Broca and Wernicke's areas are found in the left hemisphere

  If someone has a stroke in the left hemisphere, their speech will likely be affected
• Right Hemisphere

  Dominant in recognising emotions in others

  Spatial information

  A case study conducted on a woman who had damaged the right hemisphere found that she would often get lost even in familiar locations if she didn't have verbal instructions for directions also, which supports the idea, that the right hemisphere is dominant in spatial information
• Broca's Area

  Broca correctly identified the area of the brain responsible for speech

  They found not all words were equal in the Broca area and they were effected differently

  Nouns and verbs seemed be less effected but predisposition and conjunctions were no longer able to be used
• Broca was a neurologist
• One patient, named Louis Leborgne, suffered from epilepsy throughout childhood
• Leborgne eventually lost the ability to speak apart from the word tan
• Leborgne was hospitalised at the age of 30 and stayed in hospital until he died in 1861 at the age of 51
• Post-mortem performed by Broca

  1. Performed on Leborgne's brain

  2. Found a lesion on the left temporal lobe

  3. Concluded it was responsible for speech production
• Broca found a lesion on the left temporal lobe, this was the only damage found
• Broca concluded that the left temporal lobe was the area responsible for speech production, as Leborgne had developed a deficit in that area
• Broca's aphasia


  The term used today for patients who display problems producing speech
• Wernickes Area

  Wernickes area is a separate area of language processing which has a specific function

  Wernicke worked in a hospital in Germany

  He found patients who had damage near the auditory cortex had specific language impairments

  The inability to comprehend language and anomia

  However, he found that the same people did have fluent speech when they were able to access the words quickly

  Wernicke suggested this area was important for understanding language and accessing words
• The left side of the brain centres and moves the right side of the body and the right side of the brain centres and moves the left side of the body
• The right side of the brain takes the visual information from the left visual field taken from both optic nerves and the left side of the brain takes the visual information from the right visual field, again from both optic nerves

  However, areas for speech are only located on the left side of the brain
• The left and right hemispheres are connected by the corpus callosum

  This connection allows for quick communication between the two hemispheres
• Sperry studied 11 patients who had a corpus callosotomy as treatment for their epileptic seizures
• Sperry's Split Brain Research

  1968
• Sperry's research method

  1. Projected information into each visual field

  2. Controlled which information each visual field accessed

  3. Participants asked to say what they saw

  4. Participants asked to draw it

  5. Participants asked to pick out from hidden objects
• Left hemisphere


  Information presented could be spoken